Project Summary I propose to implement innovative and advanced social network modeling using dyadic, egocentric, two-mode network, and multilevel mediation analyses to answer the following research question: How do Latino cultural values and acculturation stress impact social network configurations and dynamics that could then act as protective or risk factors for substance use disorders (SUDs) and HIV risk? K99 Phase: Using my mentors' exceptional academic careers as an example and guide?coupled with training by international experts in social network analysis?I will receive mentored training in five key areas to obtain: (1) knowledge on SUD and HIV epidemiology, (2) comprehension of cross-cultural research, (3) advanced social network analytical skills, (4) comprehension of social network translational research, and (5) professional development. R01 Phase: A cross- sectional social network study will be implemented using data collected during the R00 phase (for males) as well as secondary data already collected (for females) between March and December 2015. The total sample will consist of 40 egocentric networks (20 groups of men and 20 groups of women) that will each be comprised of 13 people at least 18 years of age (N=520). I will analyze associations between: (1) SUD and HIV risk; (2) Latino cultural values (family cohesion, marianismo, machismo and religiosity) and acculturation stress; and, (3) the following social network factors: (a) individual factors: socio-demographic characteristics; (b) social factors: dyadic attachments, social support and family characteristics, direct influences from close friends or cliques (set of individuals all connected to each other), influences of network positions such as high centrality (for example, being popular), and influence from self-selection friendships based on SUD or HIV risk status; and, (c) structural factors: affiliation network structures (social venues or types of seasonal work). This K99/R00 program will not only prepare me for performing the proposed cross-sectional study but will also provide me with the background knowledge needed to submit an R01 application?based on a longitudinal design?that will allow me to understand how changes in social networks over time place Latino seasonal worker communities at risk for SUDs and HIV across generations. This information will translate into innovative and cost-effective interventions. Expected outcomes also include advances in modeling and statistical procedures for social network research and new knowledge that will inform public policy.